Vehicle Speed Sensor / Speedometer Readings

Discussion in '1994 - 1995 Specific Tech' started by k00ksta, Jul 12, 2013.


  1. k00ksta

    k00ksta Member

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    When testing the incoming voltage from the computer at the Vehicle Speed Sensor do we check for 5.0 volts in AC or DC? I have read the speed sensor is actually an AC voltage generator so this is why I question. I did replace the sensor because I was under the car but when I probed with my meter (meter set to DC) the pink/orange to grey/black wire in the harness that plugs into the sensor I only was getting 1.75 volts.

    I did test the old and new sensors on the bench against DC on my volt meter and seen it was generating power when turning it also.

    Basically with KOEO my speedometer raises to 15 mph so I am trying to diagnose this problem. What supplies the speed to the cluster? is tied to the computers VSS+/VSS- wires?

    Thanks for any help killing the last of my gremlins with this car. :flag:
  2. toyman

    toyman SN Certified Technician

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    The VSS is a gear driven permanent magnet signal generator. The generated signal is proportional to the vehicle speed. The voltage is DC. The VSS generated signal is sent to the cluster. The signal also goes to the PCM to determine the EPC pressure and shift schedule.
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  3. 5.0 Ford Guy

    5.0 Ford Guy Founding Member

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    toyman amazes me with his knowledge of the Mustangs electrical systems. Please remain on these forums until my car has gone through it's electrical problems phase ;)
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  4. k00ksta

    k00ksta Member

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    So do you know what the voltage going to that vss sensor from the computers vss+ should be I believe its pin 3 or 6 on the ECU. Or does the ECU not supply an voltage to it?

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